Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
  • C23C16/505—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges
  • C23C16/509—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges using internal electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32082—Radio frequency generated discharge
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/3244—Gas supply means
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32532—Electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32532—Electrodes
  • H01J37/32577—Electrical connecting means
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32623—Mechanical discharge control means
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/3266—Magnetic control means
  • H01J37/32688—Multi-cusp fields
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/67005—Apparatus not specifically provided for elsewhere
  • H01L21/67011—Apparatus for manufacture or treatment
  • H01L21/67017—Apparatus for fluid treatment
  • H01L21/67063—Apparatus for fluid treatment for etching
  • H01L21/67069—Apparatus for fluid treatment for etching for drying etching
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/0011—Working of insulating substrates or insulating layers
  • H05K3/0055—After-treatment, e.g. cleaning or desmearing of holes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/32—Processing objects by plasma generation
  • H01J2237/33—Processing objects by plasma generation characterised by the type of processing
  • H01J2237/335—Cleaning
  • H01J2237/3355—Holes or apertures, i.e. inprinted circuit boards
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/09—Treatments involving charged particles
  • H05K2203/095—Plasma, e.g. for treating a substrate to improve adhesion with a conductor or for cleaning holes

Definitions

• the present invention relates to plasma reactors, and more particularly, to plasma reactors
• interconnecting holes are drilled through the boards and interconnecting metallic layers are plated within the drilled holes to provide an electrical connection between exposed edge portions of the conducting layers of the printed circuit boards.
• the printed circuit board's conducting layers are defined patterns of copper, separated by layers of insulating plastic.
• the drill smear problem is the result of resin from the board, as well as bonding agents that hold the boards together, coating the inside surface of the interconnecting holes.
• the resulting smeared layers tend to insulate the edge portions of the conducting layers exposed within the drilled holes, and if not removed prior to plating of ' the apertures, individual circuits will be shielded from the- plating and, therefore, not function properly.
• wet chemistry is considered the less desirable method since it creates undue hazards for personnel and excess pollutants both in the form of vapor and waste materials that are difficult to dispose of properly.
• plasma -de-smearing is a one-step operation as compared to the wet de-smearing operation which is multistep.
• the cl y chemistry method etches back the non-me.tallic portion of the multilayer printed circuit " board adjacent to the conducting layers in " the region of the drilled holes, ' thereby providing an increased exposed surface area of the conducting layers to which the interconnecting metallic layer is subse ⁇ quently plated. Accordingly, improved mechanical adhesion of the interconnecting metallic layer results from the etching back operation.
• a particular objective of the present invention is to provide uniformly conditioned workpieces treated in a plasma reactor apparatus suitable for large scale production operations.
• the plasma reactor of the present invention is ideally suited for conditioning workpieces, such as multilayer printed circuit boards, in a gas discharge plasma.
• the conditioning of the printed circuit boards may include the de-smearing and etching back of interconnecting holes formed therein.
• a vacuum vessel having a chamber therein is the plasma reactor housing. Within the chamber is supported a series of parallel disposed electrodes adapted to have alternate polarities. In addition, workpiece supporting means are provided for position ⁇ ing each workpiece between adjacent electrodes of alternate polarities. The workpiece supporting means are disposed within the vacuum vessel chamber
• Means are further provided for directing a uniform flow of gas across the workpiece while the
• the uniform gas directing means include a vacuum vessel door defining a parabolic-surface within the vacuum vessel chamber, vertically disposed baffle plates, and at-least three radial gas inlets disposed equidistantly about the chamber.
• the radial gas inlets each have a discharge end which is directed at the parabolic surface of the vacuum vessel door and located between the baffle plates and the parabolic surface.
• Parallel arrangement of the plasma reactor electrodes, as well as the uniform flow of the plasma gas across surfaces of the workpieces, provide for the uniform conditioning of workpieces disposed within the plasma reactor of the present invention.
• each workpiece is positioned parallel to and between a pair of adjacent electrodes of the series of electrodes.
• the adjacent electrodes are caused to have alternate polarities, and a gas discharge plasma is generated therebetween for conditioning of the workpiece.
• Figure 1 is a side elevational view of the plasma reactor of the present invention.
• Figure 2 is a partially cross-sectional, elevational view of the plasma reactor .of Figure 1.
• Figure 3 is a partially cross-sectional view along lines 3-3 of Figure 2.
• Figure 4 is a partially cross-sectional, exploded view of a top channel member used in the present invention, as shown along lines 4 -4 of Figure
• Figure 5 is a ' partially cross-sectional, exploded view of means used in the present invention for carrying. orkpieces therein, as shown along lines 5-5 of Figure 3.
• Figure 6 is a partially cross-sectional, exploded view of a bottom channel member used in the present invention, as shown along lines 6-6 of Figure
• Figure 7 is a partially cross-sectional, exploded view of an end electrode retainer member use in the present invention, as shown along lines 7-7 of Figure 2.
• Plasma reactor 10 includes a vacuum vessel 12 having a generally cylindrically-shaped section 14 with a parabolically
• Vacuum vessel 12 is supported on a work surface by legs 15 which are fixed to section 14.
• a chamber 24 is defined within vacuum vessel 12.
• vacuum vessel 12 is constructed of internally welded aluminum, and door 16 and cylindrical section 14 sealingly mate at flange members 14 (a) and 16(a) , respectively, so that when required an evacuated condition is maintained within the chamber 24.
• Door 16 is provided with a viewing window 26 and further defines a parabolic surface 28 within the chamber 24.
• the vacuum vessel 12 may be, for example, 38 inches in diameter and 48 inches deep.
• a box—like cage frame 30, constructed from angle rails, is carried by vacuum vessel 12 along support members 32 which extend longitudinally through cylindrical section 14 and are welded thereto.
• Support members 32 are themselves formed of angle rails. Teflon pads, not shown, are positioned between support members 32 and cage frame 30 to electrically isolate cage frame 30 from vacuum vessel 12.
• Electrodes 34 Secured to cage frame 30 is a series of parallel, vertically disposed electrodes 34, includi end electrodes 34(a). Each electrode is ' planar in structure and approximately 2 feet by 3 feet in dimensions. While electrodes 34 and 34(a) are depicted as being imperforate, it is nevertheless anticipated -by the present invention that the electrodes may be perforated. Whereas the rear wall of the vacuum vessel 12 is shown flat, it may appear parabolic in prac ⁇ tice for purposes of structural integrity and improved pumping speed uniformity at the rear of -5 the electrode cage 30..
• end electrodes 34 (a) abut cage frame 30 along their periphery and are held thereto by means of end electrode retainer members 36.
• Retainer members 36 Retainer members 36
• End electrodes 34(a) are electrically isolated by conventional insulation means (not shown) from retainer members 36 and cage frame 30.
• opposed pairs of top and bottom ' electrode support channel members 44 (a) and 44 (b) , respectively, are . used for positioning electrodes 34 along the cage frame 30.
• Each of the channel members 44 (a) and 44 (b) are . used for positioning electrodes 34 along the cage frame 30.
• top channel members 44(a) are secured to cage frame 30 by means of screws 46;
• members 44(a) are electrically isolated from cage frame 30 by a Teflon insulation strip 48 disposed between frame 30 and channel member 44 (a) , and further by means of threading screw 46 through an electrically insulated shoulder bushing 50 as it 30 extends through frame 30.
• bottom channel members 44(b) are secured to cage frame 30 by means of screws 52 and are
• End electrode retainer members 36 are positioned on cage frame 30 so as to allow for expansion and contraction of end electrodes 34 (a) and thereby eliminate warping of the electrodes which could ⁇ bring them out of parallel alignment with adjacent electrodes.
• the grooves formed in top and bottom electrode channel members 44 (a) and 44 (b) are constructed to appropriate tolerances so that the electrodes retained therein do not warp out of parallel alignment because of electrode expansion and contraction.
• the series of electrodes which includes electrodes 34 and 34 (a) , is arranged in the present invention so that adjacent electrodes are of opposite polarities.
• end electrodes 34 (a),as well as electrodes 34 which are alternately positioned between electrodes 3 (a) and referenced by the letter G are maintained at groun potential by means of common grounding strap 60 and auxiliary grounding strap 62.
• Common strap 60 extends between"and is bolted to the uppermost support members 32. Accordingly, common strap 60
• Gtj is grounded by its electrical contact with vacuum " vessel 12 via support members .32.
• common strap 60 extends downwardly at its ends and is bolted to each of the end electrodes 3 (a) .
• Auxiliary straps 62 extending in a generally vertical manner, have one end thereof bolted to common strap 60 and an opposite end thereof bolted to one of the electrodes 34 which is to be maintaine at ground potential.
• the remaining electrodes 34 are designated by the letter H and are maintained at a predetermine R.F. potential by electrical communication with R.F. generator 64, as shown in Figure 1.
• Two R.F. feed-throughs 66, Figure 3 are in electrical contac with R.F.
• a common conducting strap 67 extends between and is bolted to each R.F. feed-through. Strap members 70 are secured by bolts to common conducting strap 67 and extend therefrom to the alternately disposed electrodes 34 which are being maintained at a predetermined R.F. potential. Conducting straps 70 are fixed to their respective electrodes 34 by conventional bolting means. Therefore, the present invention provides parallel disposed pairs of adjacent electrodes of alternate polarity; i.e., gr potential and a predetermined R.F. potential. While two R.F. feed-throughs 66 are shown in Figure 3, it is nevertheless understood that the present invention can operate with only one R.F. feed- hrough.
• the means for so positioning the printed circuit boards include hollow-slotted bracket members 74, each of which is fixed to cage frame 30 between adjacent top channel members 44 (a) as it extends longitudinally along vacuum vessel 12. Bracket members 74 are secured to cage frame 30 by means of nuts and bolts 76 and 78, .respectively, as shown in Figure 5. To assure that the printed circuit boards are not part of the electrical circuitry of the present invention. Teflon insulating strips 80 are disposed between bracket members 74 and cage frame 30.
• nuts 78 and bolts 76 are electrically isolated from bracket members 74 and cage frame 30 by. electrical insulating shoulder bushings 82.
• T- ails 84 are supported within bracket members 74 and extend through slots 86 thereof.
• Apertures 88 are formed in T—rails 84 to receive one hooked end of suspension members 90.
• suspension membe 90 can take other conventional forms than that described above, such as alligator clips or the like
• a rear wall of vacuum vessel 12 is designa by the numeral 92 and includes two exit ports 94 in communication with a vacuum pump 96 by means of conduits 98.
• the atmosphere in the vacuum vessel chamber 24 is evacuated through ports 94 by activati of vacuum pump 96. While two evacuation ports 94 ar described, it is nevertheless anticipated that only one exit port 94 is needed in the operation of the present invention.
• the gas or gas mixture which is ignited into a gas discharge plasma in chamber 24 is provided by an external gas source 99.
• Gas from source 99 flows through conduit pipes- 100, which are secured to vacuum vessel 12 by conventional conduit fixtures 102, and exits into chamber 24 from three radial gas inlets 104 equidistantly positioned about vacuum vessel 12.
• Radial gas inlets 104 are elbowed and positioned forwardly in cylindrical section 14 so that the gas exiting from their discharge ends 106 is directed towards parabolic surface 28 of closed door 16.
• vertically-disposed baffle plates 108 are fastened by conventional means to cage frame 30 in a forward position in cylindrical section 14 and extend from cage frame 30 to the interior surface of vacuum vessel
• each radial gas in-let 104 extends through openings 110 in baffle plates 108 so that discharge- ends 106 are positioned between baffle plates 108 and parabolic surface 28.
• the directing of the discharge gas toward parabolic surface 28, and the baffle plates 108 provide for a uniform flow of the gas across the surfaces of the circuit boards upon the generation of a gas discharge plasma.
• the printed circuit boards to be conditioned i.e., de-smeared and etched back, are disposed within chamber 24 between adjacent electrodes.
• Door 16 is secured in its closed position and chamber 24 ' is evacuated to a pressure of approximately 50 millitorr by means of vacuum pump 96.
• Vacuum pump 96 is preferably of a type which is capable of at least 120 cfm operation.
• a gas mixture typically oxygen and freon in ratios of 7 to 3 or 8 to 2
• the R.F. generator 64 capable of operating in a frequency range of 30 to 60 KHz with a power potenti of 4800 watts, is activated to establish a predeter ⁇ mined R.F. potential at alternately positioned electrodes 34 having been designated by the letter H in Figure 2; end electrodes 34(a) and-those electrodes 34 designated by the letter G are, of course, maintained at ground potential.
• the gas mixture is ignited into a discharge plasma liberating free atomic oxygen and free fluorine fpr the purpose of removing drill smear and the etching back of non-metallic material of the multi ⁇ layer printed circuit boards.
• each printed circuit board is positioned between a pair ox adjacent electrodes and the plasma is struck along a surface approximate parallel to that of the printed circuit board itself improved batch uniformity across each circuit board and from circuit board to circuit board is realized.
• the operation of the subject invention is also useful in the pretreat ment of laminate panels for the purpose of improving their bondability with laminating adhesives.
• the apparatus and method of the present invention are similar to that discussed above, although the process time and power requirements are substantially less. Accordingly, the present invention provide a much sought after improvement in the plasma art, whereby large scale production and uniform condition ing of workpieces, such as multilayer circuit boards, are readily obtainable. While the invention has been described with respect to a specific embodiment, it is not limited thereto. The appended claims therefore are intended to be construed to encompass all forms and embodiments of the invention, within its true and full scope, whether or not such forms and embodiment are expressed therein.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Analytical Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• General Chemical & Material Sciences (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Power Engineering (AREA)
• Plasma Technology (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)

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• 1980
  • 1980-05-03 US US06/152,688 patent/US4289598A/en not_active Expired - Lifetime
• 1981
  • 1981-09-14 WO PCT/US1981/001224 patent/WO1983001075A1/en not_active Application Discontinuation
  • 1981-09-14 JP JP56503119A patent/JPS58501484A/ja active Pending
  • 1981-09-14 EP EP19810902566 patent/EP0088074A4/de not_active Withdrawn

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